This application claims the priority of German application 10124852.0, filed May 22, 2001, the disclosure of which is expressly incorporated by reference herein.
This invention relates to a temperature sensing device for an internal-combustion engine. The invention also relates to an air flow temperature measuring process.
Conventional temperature sensing devices normally comprise sensor elements which permit temperature sensing based on thermodynamic measuring principles, such as a temperature-caused volume change of a fluid, or on the basis of electrical effects, such as changes of a specific resistance. By way of electric lines or thin pipe lines, these sensor elements are connected to a central sensing device. Sensor elements for sensing the engine temperature can be arranged in the area of a cylinder head. Sensor elements for detecting an oil temperature are preferably provided in a line section situated downstream of an oil pump. Sensor elements for detecting an engine intake air temperature can be arranged in an intake line of the engine in front of or behind a filtering device.
By sensing the temperatures of the intake air, the cooling water, and the oil, it is possible to optimize the operation of the engine, particularly with respect to exhaust gas quality. The numerous sensors as well as their coupling to a central engine management unit, however, require high mounting-related expenditures.
It is an object of the invention to provide a temperature sensing device by which at least two measured temperature values advantageously taken into account during the operation of an internal-combustion engine can be sensed in a favorable manner.
According to the invention, this object is achieved by a temperature sensing device for an internal-combustion engine having a carrier structure, a first sensor element accommodated on the carrier structure, a second sensor element accommodated on the carrier structure, an engine air feeding device for feeding an engine intake air flow to the first sensor element, and a radiator air feeding device for feeding a radiator air flow passed through an engine radiator to the second sensor element. The carrier structure is arranged in an area in which the two air flows run adjacent to one another.
As a result, it becomes advantageously possible to centrally sense, by way of a compact and advantageously mountable constructional unit, the temperatures of the two air flows. In this case, the obtained measuring signals can be coupled into a cable tree system provided on the vehicle side while cabling expenditures are reduced. In a particularly advantageous manner, it is possible, for example, prior to an engine start, to check the method of operation of the two sensors with respect to one another and, if necessary, carry out a joint calibration of the two sensors. Because of the local proximity of the two sensor elements, a particularly informative comparison of the respectively sensed temperature values will be possible. Since, during operation of the internal-combustion engine, the temperature sensed by the second sensor element cannot be below the temperature of the intake air, a particularly reliable function testing of the temperature sensing device can be implemented.
The two sensor elements are preferably, by way of the carrier structure, combined with a constructional unit. This results in advantages, particularly with respect to mounting.
According to one particular aspect of the present invention, the two sensor elements are connected by way of common cabling with a cable tree branch provided on the vehicle side. The cabling assigned to the two sensor elements can in this case be connected with the vehicle-side cable tree branch on the vehicle side by way of a common connector plug structure.
Advantageously, the connector plug structure is constructed integrally with the carrier structure. The carrier structure is preferably made of a plastic material and forms a separating wall which separates the two air flows from one another at least before they sweep over the sensor elements.
According to a particular aspect of the invention, the carrier structure is preferably constructed integrally with an air guiding element. This air guiding element is preferably an engine intake air guiding device.
As an alternative thereto, it is also possible to integrate the carrier structure into a blower suspension or a radiator tank of a vehicle radiator. The two sensor elements are preferably arranged adjacent to one another. This results in a particularly compact construction.
The carrier structure is advantageously arranged in an area in which a line device of an engine intake air system extends past a radiator blower. In this area, the engine intake air system is preferably coupled with an engine radiator or a radiator blower device.
It is possible to provide another sensor element, which is also mounted on the carrier structure, for detecting the cooling water temperature. This sensor element preferably is connected also by way of the common cabling to the vehicle-side cable tree.